1. Field of the Invention
The present invention relates to a method of forming a protective film with scratch-proofness and ultraviolet cutting characteristic on a surface of a plastic car part.
2. Description of the Related Art
Thermoplastic materials which can be easily recycled are widely used for car-use parts, or the like, in order to reduce weight and protect the environment. For example, a polycarbonate resin is mainly used as a lens material for a car headlamp to reduce weight and provide high impact strength. If such a plastic material is used for an exterior part of a car, there is, however, a weak point that the exterior part is apt to be scratched because the material itself is low in surface hardness and that the exterior part is deteriorated by ultraviolet rays and heat radiated from the sun to thereby cause discoloration, deformation and reduction in strength.
To compensate for the weak point, a protective film with scratch-proofness and ultraviolet cutting characteristic was heretofore formed mainly on a plastic surface, for example, by spraying acrylic paint.
The shape of such a plastic part used in a car was, however, a diversified and complex three-dimensional shape. In a surface coating process for spraying paint onto such an part, it was difficult to form a protective film with a uniform thickness. Moreover, coating efficiency onto a plastic surface was so low that most of an organic solvent might be wastefully released into the atmosphere or the paint might be deposited on an undesirable surface.
Therefore, it is required that a protective film of uniform thickness and good quality with scratch-proofness and ultraviolet cutting characteristic and the like be formed on a plastic part having a diversified and complex three-dimensional shape while wasteful release of an organic solvent, or the like, into the atmosphere can be avoided.